scrid

Hello everyone!
I am having some trouble with my 94 4runner 3.0 and was hoping to get some ideas or insight before I start replacing parts.
it's a 1994 4runner with a 3.0 and 116,000 miles on it.
Engine was rebuilt less then 10k ago.
At that time I replaced the TPS and knock sensor. I did not replace the injectors. For the last 3 years it has been running just fine.
Recently one day I started it and it would run for about 10 seconds really rough and die. I could hear a definite miss and had to raise the throttle to keep it running until it cleared it throat and then would idle fine. It runs fine except for sometimes at a stop light when I go to accelerate it falls on its face and dies.
It has no codes.
It doesn't happen all the time though. The rough idle at start up seems to happen anytime I don't start the truck for a couple days.
I replaced the fuel filter when I rebuilt the engine but thats been about 4 years ago.
Starting to wonder if I may have bought some bad fuel? Or if the filters plugged.
Anyone else had a similar problem and or suggestions?
Thanks. Chris.

MaK92-4RnR

Sounds fuel related. Could try changing the fuel filter again. its about 17-18 bucks from Toyota. Cant go wrong with starting small.

rattlewagon

Sounds like an ignition/spark issue.

jimbyjimb

iTrader: (1)

There could be any number of problems but assuming the engine is in good tune and is receiving good fuel/spark you could be looking at a sticky EGR or a vacuum leak.

scrid

Thanks guys, yesterday I changed the fuel filter which was hard to blow through but I,ve seen worse. Drained a gallon of fuel from the tank to check for water,...none found.
I also pulled the vacuum line from the fuel pressure reg. but found no fuel in it.
Tuned the engine up, and replaced the first rubber intake boot off the throttle body because it was cracked. I will be starting it later this morning to see if it still does it.
I was wondering about the EGR valve possibly sticking as well. Or the CSI leaking all the time. I had previously unplugged the CSI to see if that would help, but it didn't, so if it is the CSI it would be mechanically leaking inside. I was wondering if I cracked the CSI fuel line to see if it holds pressure overnight? Maybe that thing leaks all my fuel pressure out into the intake plenum overnight and fouls my plugs?

Gamefreakgc

Don't rule out a vacuum leak. Your cracked intake boot may have been the culprit. If a vacuum leak is big enough it'll cause it to stall. Do a complete visual inspection of all hoses or try the carb cleaner/propane trick. Probably not the EGR, if it's clogged you'll just get poor emissions ratings, the truck will run just fine without it (some models do not have an EGR anyway).

scrid

Well it started and ran fine yesterday. I will run it again today and see how it does.

jimbyjimb

iTrader: (1)

If an EGR is sticky and gets stuck open or partially open at idle it will cause poor running conditions at low engine speed. Removed or plugged makes no difference obviously, but if the valve sticks open at idlethis is a common symptom. Especially on older vehicles. Easy to test as well.

scrid

It's still doing it. I started it yesterday and it dies right off the bat. Cranked it again and got it running but had to keep my foot in the pedal to keep it running. It runs really rough and I can see soot like smoke from the tailpipe through the side mirror. It runs really rough like 3 cylinders are not firing. If I hold the pedal midway I can get it to smooth out clear its throat like the other 3 cylinder come alive again,... and then it runs decent and will idle on it's own. I'm leaning toward that CSI leaking down pressure in my intake overnight fouling plugs?, however I loaned my OEM service manual to a friend and have not got it back from him yet.
Whats the procedure for testing the EGR valve on the 3.0?
I thought about cracking a fuel line this morning before I start to see if it is holding pressure in the fuel system. Or removing the CSI from the manifold, leave it connected to the line and electrical connector, place it in a plastic baggie to see if it leaks in there.
Thanks.

Gevo

If you are getting what you described from the tailpipe, I doubt it's an EGR issue. But, it is easy to test so do it.

HOpefully it is unburnt fuel and not coolant that is coming out the pipe. I don't think you mentioned a tune up with your rebuild, although spark problems from tune up parts don't really cause an intermittent problem, they would cause a more constant problem.

Borrow a fuel pressure tester from autozone and test the pressure. see if it is to spec. Check your coolant level, are you losing coolant anywhere?

scrid

No I'm not losing coolant.
I did a tune-up at the time of the rebuild and just changed plugs the other day.
All 6 plugs were sooty, but still looked good. I replaced them anyway.
The sooty plugs still lead me to a rich condition.